MQTT UDP Viewer Help
MQTT/UDP Viewer is a desktop application written in Java and, consequently, it can run on any operating system.
Viewer's main screen is divided in to three parts. All of them show MQTT/UDP traffic from network.
Upper part shows current values of items. Each item is updated as new value arrives from net.
Middle part is a scrolling log of all incoming messages.
Lower part is a list of host IP addresses. It shows what hosts messages come from.
You can write incoming data to log file, see "File/Start log" menu or press Ctrl-L. Note that F5 key stops logging too.
Use F5 key or Display/Update menu item to start/stop UI update. There's also a toolbar button: 
Show or hide host list section at screen bottom
By default application sends replies to incoming packets accordint to protocol specification. You can mute replies by unchecking this menu item. This is handy to debug what is going on without intervention.
By default viewer pings world. You can disable it with Send/Ping menu.
You can send data too from Topic editor screen, which is shown when you press 
toolbar button at the top right of main screen.
By default topic editor listens to incoming data and updates itself. If you want to change and send data turn off update first, press top right toolbar button 
.
Now double click on value to change and enter new data. Press leftmost button in the same row to send changed value to network.
Next button 
sends SUBSCRIBE packet to ask some other node to PUBLISH its value for this topic.
Last button in a row, 
, selects between broadcast or direct to host transmission. By defalut program broadcasts topic value, but if this button is pressed, value will be sent to IP address in Host column.
Top left toolbar button 
lets you create new topic row.
Next to it is a topic search button 
, press it to find topics in a long list.
Some MQTT/UDP nodes implement remote configuration protocol. This interface used to work with such nodes.
Press 
toolbar button on main screen to open configuration window.
If there is a node which supports passive remote configuration, this window will contain a tab with configuration items for that node.
Enter correct parameter values and press
toolbar button to send all parameters to node. You can also send settings item by item pressing corresponding button next to the item you want to send.
Use to request current values from node. If current value in entry field is different from setting active for node, 
button will be available. Press it to revert to current active setting value. You will loose local modifications.
See MQTT UDP message content specification for implementation details.